Automatic toll-switching telephone system



Nov. 11, 1930. w. w. CARPENTER ET AL 1 0 AUTOMATIC TOLL SWITCHING TELEPHONE SYSTEM 7 Filed May 4, 1929 s Sheets-Sheet 1 Novj. 11, 1930. w. w. CARPENTER ET AL 1,780,906

7 I AUTOMATIC TOLL SWITCHING TELEPHONE SYSTEM Filed May 4, 1929 8 Sheets-Sheet 2 Nov. 11, 1930. 7 w. w. CARPENTER T AL 2 1,780,906

A UTOMATIC TOLL SWITCHING TELEPHONE SYSTEM Filed May 4, 1929 8 Sheets-Sheet 3 fizz). H55 F/QZ. H34. H525. H626 /-75.7

Nov. 11, 1930. w w. CARPENTER ET AL 1,780,906

AUTOMATIC TOLL SWITCHING TELEPHONE SYSTEM Filed May 4, 1929 8 Sheets-Sheet 4 Q Q Q y'\ g glllllllwz Y Q Mi li-H T u n Q Q S Q 1 1? a F9??? aw s xr iin MM: RR A f 1 \3 wi b a Q '8 W U IN Q $2 H I IEIIIIIIIHP I a IIIIIIH'l I M H" ATTORNEY AUTOMATIC TOLL SWITCHING TELEPHONE SYSTEM I 8 Sheets-Sheet 5 Filed May 4, 1929 v 973mm WWW/UB5. WW GARPENTf/i' By a lffE/FSEY 47'TORNEY Nov; 11, 1930. w. w. CARPENTER ET AL 8 AUTOMATIC TOLL SWITCHING TELEPHONE SYSTEM Filed May 4, 1929 8 Sheets-Sheet 6 CIRCUIT Nov. 11, 1930. w. w. CARPENTER ET l- 1,730,906

AUTOMATIC TOLL SWITCHING TELEPHONE SYSTEM Filed May 4, 1929 8 Sheets-Sheet 7 QBQ \R NNQ MA 8m Nov. 11, 1930. w. w. CARPENTER ET AL AUTOMATIC TOLL SWITCHING TELEPHONE SYSTEM a Sheets-Sheet 8 Filed May 4. 1929 WVENTOHS. W. W CARPENTER f? E. HERSEY BY fiJmw Patented Nov. 11, 1930 UNITED S-"IATES PA E QFHCE i i WARREN w. .cAnPnNm'nR, or oUEn-ns vlnnaenfnnn RALPH n; nnnsny, oniBnooK new YORK, ASSIGNORS T0 nnnnrnnnrnonn LABORATORIES,"INCORPORATED, on NEW Y0fR-K;'N. Y., A'oonPonA'rIon on NEW.YORK r v g AUTOMATIC roLn-swnromiio TELEPHONE sys'rn vi r ris filed tra 4, 1929. Seria1 No. 360,458; a

This invention relates to a telephone exchange system, and more particularly to a system in whichconnectiOns are established between subscribers lines in different offices :over toll trunks by automatic switching mechanism under the control "of a toll operator in theoriginating office The, objectot" the nvention 1s to economize 1n the amount of apparatus required for the toll operator to controllan'd superviset-he establishment-of such connectonsandto simplify the circuits required for establishing and ma nt iningeu h conn tio 7 In th stably hmen re'f enn t on ,0

- irornoffices of a dial switching exchange area for which toll rates should 'be assessed for service, it is customary for a calling subscriber insuchan office who desires to obtain a connection with another subscriber at a remote point to dial 'a number whereby connectionis first .obt ined w th a e l p erator', who rthen proceeds to obtain thexdet V I v t v 1n the terminating dial switch ngoffice, who TGCGlVGSJllStI'HCtlODS -for'term1nat1ng .the con sired connection and to supervise theassess mentofthe requ red toll charge.

Several methods of establishing such 611; connections have heretofore been proposed for use in connection with panel type dial switching systems. In accordance with i one of these methods. disclosed "bytw ay of eX- I ampleinthe patent tolGooderham 1,506,743,

grantedSeptember 2, 1924, thecalli g subscriber desiring an outward 'toll con nection dialsithe machine switching A operator.s position of the office 1n ,whichthe calling line terminates and transmits gtoher, hisown number and the number of the desired 'sub'r' scriber. The A operator thenproceeds by ldicator. pp s tl aer t 401ml swit h g: pparatusofthe termir atingfoifice and a plumeans of a sending equipment to establish office atrunk lineove'r Whichthe tollco nnection may be completedand gives the cord:

less operator the-necessary information for establishing a connection back to' the calling linel Thisis accomplished. by the cordless operator by means of-asender at her posi-' tion'and selectorrswitches. Assoon as thisv connection is established back; the connection 1 equipments each including a key Y set, there being a positionequipment individual to 'eachtoll operators position, a plural-ityot formerly established throi1gh the A opjeratorsposition to the'toll operatorsposi-fl tion is dismissed. The toll operator then proceeds to cause a connection to be established'to the desired line, the final; connection extending from the calling'lin e through the selector switches set up by the vB icor'd-l lessoperator overthe trunk extending to the it toll operato rs I position a and thence by the toll line to the desired subscribers line; 7 Inward connections" from distant toll points. are completed according to this method over the tolloperators cord circuit andjmeans'" to A. C; Powell 1,577,076 granted March 16,

1926. According to this method an inward toll connection is handled by a tolloper ator" nection overthe tollline and utilizes so-called 75 keyindic'ator equipment at her position to; either terminate the connection by dial switching apparatus if the 'desiredlineterminates in an office equipped with selector switching mechanism or by callfin dicator apparatus if th eidesired line terminates manual office; Thekey indicator apparatus.

comprises .a' plurality of operator srposition register senders for either setting the call in- I r -In accordancei'with the present invention outward tollJconnections may be v established from a, dial switching'oflice either of two,

ay er se" P th eXtQn 'Q h e -v.

nection' with an 'A? operatorspo'sition,

which operator then passes the call to a P change area, In a large 'ex'chang e' area the} L subscriber would dial a number to obtain 'con- 2- r a 4 obtain a connection ep lt rs position.

cording tolloperator who makes out a ticket for the call and passes the information to a toll switching operator. The toll'switching operator then buildsup the toll connection to the desired toll point and obtains connection with the desired subscriber and thenf builds back a connection over the dial switch- 1 ing equipment of the originating office to the i calling subscribers line, the original connection from the calling line to there-U cording operatorthen being dismissed; 21nsmaller exchangeareas thecall would behandled in a similar manner, except that the subscriber would dial such a number as to 'j- Callsgincon ing from "a switchingIofiice in. which the desiredcsubi f scribers hnet nninates, and then setting the i l swi c gappar t 1 s h Office y meansof the improved apparatus at her p0 sition associated with such trunks. I I

switching: operator isthusjenabled to serve The toll toll connections to connecther position automaticallyi-with subscribers lines in dial switching ofiices to complete outward calls or I ,to connect her position with such subscribers? I "lines to'terminate inward calls." I j 1 I I The toll switchingoperators equipment in I accordance with the present "invention has,

' been very 'muchsimp'lified'overj the key indif Ica tor typepreviously described .in that the operatorsis en able dto connect with trunks ex- I tending to dial switchingiofiices on a straight-f, forwardjbasis. QAcco rdi'ng. to, one/ embodi- V ment "of 'thei invention v disclosed herein by of illu'stration, the, toll operator is provided fwith a: ten buttonx key set common to the cords other position which becomes asso ciated with a cordof her position' when she I takesit for use.' {Associated with eachgroup for trunks extending to a dial switchingoflice towhich she has access isa group of link c'ir-, cuits eachcoinprising Va step bystepstrow e ri l're r nk 'fi t a ep-by fi p 'senderfselector, 'F or controlling the posi- I tioning of the'dial switching equipment in ,I

" which the interofiic e ftrunks terminate and "over which access to dial switching sublscrfibersf lines "may be had, a plurality of; common {registerf'ty g i senders is c p o ided;

. Whenthefop'eratorplugs into a trunkex tending ro n oflice in which "a desired sub scribers line terminates an idle linkfcirc'uit istaken for useand through the operation the'trunk finder and sender selector therev c iof, an idle sender is'associatedwith thetrunk c which the operator has taken for use. By thev manipulationofherkeyset the operator may a then set thefregisters of such sender in c'accordance with the designation of the desired line, whereupon the sender proceeds to set Eord circuit and the trunk circuit. same talking conductorsgsignaling impulses are also transmitted between the. sender and "the position apparatus to connect the "opera- I I I distant tollfp oint I are-answered the toll switching operator who.thenterminatesthe"call by plugging directly into anflidl'e trunk eXtend ingto the dial tion, including a set of pulsing keys. I I

Fig. ZQSIIQWS additional equipment of the I operators position I including I telephone I ar'ejdisclosed. i V w H Figs. 6, 1 and 8'show asender circuit, Fig.

6 disclosing control "relay ,"equi'pinent of the I Ysender,1F ig.-7 disclosing the counting: relaysg Y 10f the selector controlling portion 'offthe' c the selector switches to connect with such line.

two current strengths andof either negative or positive potential -in code combinations over the talking conductors ofthe operators torsl key set as soon as a sender has become attachedtothe trunk which the opera tor has taken for us'e,to inform the operator directly with 'the"'tollf"when thesen'derhas completed its registration function'sandthat theikeyset has been I disasso cia ted 'from such sender, andfto in,- c I .forin the sender'whether the operatorspo Over the sition is functioning on in ward or outwa rd 3 sender for applying ringing current directly For ainiore complete understanding of this a toll calls.,-. Provision" is also'made'f in the 1 5 invention reference "Imay be had to the, at-

' fta ched drawings which:

Fig. l sho ws an operat'ors?cord circuit for extending incoming toll connections to trunksextendingto a dialswitching oflice' anda per-r tion of the equipment of an joperators posi headset. a v 7 I Fig. '3 showsa trunk'lcircuit terminating in a jack accessible to the operatorsccord c1 r- 1 cu'it of Fig. 1 and In an incom ng selector. of f adial switchingoffice and a diagrammatic 5 representation of -a finalselector' and called I subscribers line.

Figs; 4 and 5 taken togetherishow a link circuit' for: associating the sender such 'as' I, is

disclosed in Figs. 6, '7 and 8 with-the trunk circuit of Fig. I 3. .In Fig; 4 the trunk :finderf and -in Fig. 5' the sender tinder of thelink sender and Fig.8 showing the registerre -QI Fig.9 is'a diagram showing the Inanner'in embodimentofthe inventiom r I Thetrunk finder 4:50 of Fig, 4 may be of: the

well known Strowger type, having'both royi;

tarry andvertical steppingrnovem'ents but being used as a hin'iti i igl switch} it i n l fl "I equippedwith a vertical g'roup commutator and commutator brush.'- 7 In addition I is tion circuit shown in Figs. 1 and '2'w'ith the exception of key pulsing equipment areof the :Patent 1,67 5,956 issued to equipped with three additional brushes to afli'ord'additionalpoints of access to control conductors extending to trunk circuits. The sender finder 5500f Fig. 5 is of the. Well known step-by-step rotary type having no definite normal position but always rev ma-inlng-standing when idle onthe terminals of the sender last used in extending aconnec-v tion.

The incoming selector 325 and final selector 350i diagrammatically disclosed in Fig. 3 are of the well known panel type but are more 1 particularly of the toll switching type disclosedin' detailinPatent 1,575,299 issue-dto W. C. Weaver, March2, 1926. v

The toll operators cord Circuitand posigeneral character shown and described in July3, 1928.

stcbilis hment of an inward connection It will be assumed. that a toll call is incom- -ing to. the operators position of Fig. 1 and that the operator answers the call on the toll line by. plugging the pluglOO into the toll line jack 101. She then depresses her cord key 102 to the right into the talking position. A

- circuit is thereupon establishedfor relay 103 extending from battery through the lower winding ofrelay 103, the uppermost contact" of key 102, conductor 104to ground at the normal contacts of relayr200.- Relay 103 coupon energizing closes at its'lower contact a circuit extending from ground at contact 105' of key 102 over the lower contact of relay 103, conductor 106 in parallel through the windings of relays 200 and 201to battery. These relays thereupon operate, relay 200= removing ground from condu-ctor 104 to prevent another cord relay such as relay 103 from oper- V ati'ng, and connecting ground toconductor 107 whereupon a circuit is established through the upper inner contacts-and upper Winding of relay 103 to battery tohold relay" 103 locked so that as long as the key 102 is in its op'erate-d position-relay 103 individual to the cord circuit and relay 200 common to the cord circuits of the operators position are held operated. Relay 103 splits the cord circuit and associates the'gro'up ofcondud tors lO8- with the cord circuit;

The operation of relay 201 connects the tip ring talking conductors 203 and 204 of the operator s headset circuit over con ductors 109 and 110 extending to the left or monitoring contacts of thekey'102 and opens conductor 111; If at this time the key 102 of another .cord circuit of the operators position is operated to the left or monitoringposition the operator will-be able to talk-or listen on 'both cord circuits, but will be able to splittransfer or key pulse on only the cord circuit, the listening keybfwhich hasbeen L. F. Porter on operated to; the right or talk-ing position. The functions ofv thesplitting key: 21 1, talk ing and monitoring key 102*andringing key" 116 for. enabling theoperator' to talk, n1'oniitor or ring on either end ofthe cord circuit are-fully described inthe patent to Porter above referred to and will not therefore-be discussed in detail'herein;

Upon the operation of key 102 a circuit is also established from high resistance groundv on the sleeve. of jack: 101 over the sleeve of plug 100, contacts 112 of key 102, conductor 113 to' battery through the windings of re'-" lays 205 and206. Relay 206 upon operating closes an obvious circuit for'relay 207. *Relay-205 being marginal, :however, does-not operatelat this time." At its inner upp'er contact relay 207 connects ground through high.

resistance 20-8Jto conductor 209 toprevent a false operation of the rear cor-d supervisory: lamp 1l4,'shouldithe operatordepress a'talk key of a repeater cord ofi-her'positio'n to the-talking position eitheraccidentally'or otherwise with such cord circuits normal. Ataits upper back contact. relay 207 disc'on meets the busy test conductor 210 of the op erators headset from the tip of the answer-' ing plug 100 and "at its outermost upper and.

lower front contacts establishes a talking circuit which may be traced from conductor 203, over the uppermostwfront contact of relay.207,the upper normal contactlof'split ting key 211', conductor 212,.the uppermost normal contact ofrelay 115, thei uppermost alternate: contact ofrrelay' 103, the upperright normal contacts ofringingkey'116,

over the tip contacts of plug 100 and jack 101, thence'over the toll trunk,1returning over the ring contacts of jacks 101 and plug.

"100, the inner lowenalternate contact: of

relay 103, the lower back contact of relay.

115, conductor 117, the right lower normal:

'contacts of key 211, the lower front'contact of'relay' 207' to conductor 204:: Theoperator is now enabled to receive instructions over the toll trunk forl theturther extension of i the connection. 1

Having received instructions and ithaving' A circuit is thereupon estab== conductor 213,-the upperleftnormal 'contact-s of key 211, the upperback contact of relay -214to th'e'test lead 210'. .It' will be ceiving a busy click in her headse'tinserts the 'plug* 11 8' into 1' ack" 301. A 'circuit' l is assumed that the trunk terminating i1rj'ack'"" .301 testsidle and that the operator on re-- ling closes atits innermost upper contact a shunt aroundthe lower winding of relay 502 'operating looks from off-normal ground on conductor 509 over its innermost lower front contact and lower winding, conductor'513 to battery at the back contact of relay 413'and at -its uppermost back contact and innermost :lower contact opens the initial operating and locking circuits of relay 507. Relay 507 thereuponlreleases. 4

At the trunk circuit upon the operation of relay 306 a circuit is establishedforrelay 304 extending from battery through the winding of relay 304, over the upper front contact of relay 306t0 ground at the-upper contact relay 303 and transfers the circuit of relay 306 from the lower contacts of relay 304 through its own lower contacts. Relay304 upon operating locks to ground at the upper contact of relay 306, and disconnectsground from the common start conductor 305 atits inner lower back contact thereby releasing group relay 400, if there'is at the time no other trunk'in the samegroup in a selectable condition.

.H'tmt2 ng 7501' anidle s ender At the time relay 501 operated immediately following the starting of the link circuit a circuit was-also established for relay 514 extending frombattery through the winding of relay 514, over thelower back contactof test relay 515 to ground at the lower front contact of relay 501. At its upper front contact relay 514' establishes a saturating circuit for the test relay 515 which may be traced from battery through the lower winding of relay 515, the front contact of relay 514 to ground through the middle winding of relay 515. Relay 515 does not, however, become-energized suificiently to attract its armature s. At its lower contactrelay 514 establishes a circuit for the stepping relay 516 of the sender finder 550 which extends from battery through the winding of relay 516, the had: contact of stepping magnet '517, the lower contact of relay 514 to ground at the upper back contact of test relay 515'. Relay 516 upon energizing connects the winding of the'stepping magnet 517 to ground at the upper back contact of relay 515 whereupon magnet 517 energizes opening theenergizing circuit of stepping relay 516. Magnet 517 and relay 516 thus reciprocally control each other thereby'advancing the brushes of the sender finder 550 step by step in search of an idle sender. As soon as'a-terminalset is reached to which an idle sender isconnected'a circuit becomes established for test relay 515* extending from ground through the middle winding of test relay 515, the upper front Contact ofrelay 5 14,thelo'wermost back contac'tof relay'512,'[the upper winding of relay 515, the "innermost upper front contact of relay 501, brush 518,-con'ductor 5'19, back-conta'ct-of relay 600 to battery through the inner right back contact of relay 601. Relay 1 515 now receiving current through all of its'windinvs o jerates 'uickl lockin in a circuit extending from ground, over its upper front contact'ancl'upper winding, thence as traced to battery at the back, contact ofrelay601,

opening at' 'itsupper'back contactthe' operating circuits of relay-516 and magnet 517 and opening at its lower back contact the operatingcircuitof relay514.

After an interval measured by its, slow releasingcharacteristic relay 5'14 deenergizes and if at thist-ime the trunk finder has completed its operation and'rel'a'y 503-has operrelay 512, the lower intermediate front contact ofr'elay 503,'the intermediate lowerback contact of relay 1512; the upper back contact Offrelay 514,*th'e lower: front contactof' relay '51 5 to ground at thelower front [contact of relay-i501. Relay 512 uponjenergizing closes a. ,11-'01ding circuit for itself-extending from battery through its winding,'it's next to inner most lower contact'toground at the intermediateupper-contact of relay 503,0pi1s at its .brushes'41 4 to417 inclusive'of finder 450 to brnshes 520 to 523 inclusive ofsender finder 550, establishes a circuit extending-in par allelthroughfthe windings of relays 524 and 525 over the upper front contact of relay 512,

intermediate windings of relay [602, the left normal contacts of relay 603 to ground at the ated a circuit is efstablishedfor'relayf512 eX-.

"tending from battery through-the winding of contact of relay 303 over its own inner upper contact independently of the upper front brush 526, conductor 527 through the'left and inner left contact of relay 604 and at its next 7 to upper contact connects battery through high resistance 533, the back contact of relay 524, conductor 534, brush 423, conductor 424, through the upper, winding of relay 302 to the sleeve of jack 301 for the purpose of marking the trunk busy so long as the link circuit isengaged therewith. Relays 525 and 602 operate in the circuit traced butrelay 524 being marginal does not operate; At its upper contacts relay 525 bridges the upper native holding'circuit for relay 512 for holdlo Y ing relay 512 operated following the,release o l yw i r I Should a second trunk of the]sameig'mllp be selected at this ltimewith relayo500 o-perated and relay 507 deenergized':andithegroup relay 400 be operated; relay 400, will again a mark the lowermost 'cornmutator terminal 407 asbetore, but willnow startthe trunk finder lnorrnally having firstchoicei. access to the I 7 start circuit extends from giround-attheback group of trunks-in1 the firstlevel of its bank andjin'thetenth' levelof finder A150. 1 This contact of relay 401 ;oyer the lower. front contact rof'relay 400, lower normalcontact's 'of jack 4 02, conductor 403, the 'loWerrnosttroht contact of relay 500, the innerinost upper ibackfcontactof relay 507, conductor 528', the lower normal contacts ofja'ck 419, thence jthrough the relay of that link "corresponding to relay .501": Since-theco ninutatorisegin ents r andbank multiples areislip-inultipledg-in the .well known manner the line finder started will step'verti'ca lly to its tenth bank level "when it will be arrested by its commutator brush corresponding to brush 406 engaging"- thetenth segmentof itscoinmutator which is n ultipled to the segment l07. 3 In a similar mannershould other trunks be place infacallr ing conditionin the 'sarneg trunk I group'- the start conductor 305 willbe extencled to'start succeeding" linefinders which normally 'have first choice access to othergroups of trunks.

This starting arr-angernentis-in accordance with the well known so-called paddle-wheel start circuitarrangement, 4 a

;At "the sender upon the operation ot relay 602 an olovious circuit is established in pari allel-throu gh the windings of off-normal re- .lays 601' and 60,5. RelayGOl upon en-regizing removes battery at" itsi'innerright back con-i tact, from the test :lead 519 thereby releasing [test relay 515 in the link circuit which in turn :opensthe holding circuit of 'relay' 501 which thereupon releases. Relay; 601 1 also opens the operatingcircuit of the "make busy f 1 relay .600,wicloses at its inner left front contact acircuit -from ground through both windings: of difierential relay 640 to battery and closes a circuit for relay 800 which may be traced from battery through the winding of relay 800, conducton 801', left back contact -ofgrelay 606 to ground at the inner left front I cont-actof relay 601 Relay'6 10 beingdi'fiep ,enti'a'lly wound doe snot operate at this time. ltela y 0 upon operating lockspoy'era circuit extending through its windingland the winding 'of'relay 802ifthefii1nr left front "contact o'frelay 80'0;'th e left backcontact of relay 803 conductor801f'to ground at theinner left front contact ofrelay 601. Belay v 802 being shunted at this time," hoivev'er fdoes not operate inthislocking circu'itl ltelay 800 also establishes a circuitfor ope'rating relay' 606, which may be traced from battery through the; winding and inner right" normal contacts ofrelay'.606,conductorE607,oyeritlie left fro'ntcontact of relayz800 to groundas previously traced at the-inner left front con tact of relay 601. NVith relay 606 operated the shuntr'around the windingof relay 802'is l 70 removed and relay 802 operates. At'its inner right front contact relay-606 locks directly V to ground at the'inner left front 'contactof relay 601, opens its .owninitialvoperating ;cir

;cuit and at its outer left back contactopens m it thejinitial operating circuit of relay; 8 00 The purpose of relay 606 'isto prevent the reoperation of relays 800 :and 802 "after the first digit of the desired"subscribers,nuniber' has beenset upby the operationot the opereo I .ators key set; i In addition relay'606 establishes acircuit from ground'at the inner left v front contact of relay 601 through theright low resistancewinding of relay6 l0, over the '7 outer'rig'ht contact of relay 606,the"inner I right front contact of relay 601,the back con- 7 tact ofrelay 600, conductor 519, brush 518, i

the innermost upper back contact otirelay 501, thenext tozlowerniost front Jcontactpf relay 5-12to'the uppermost back contact ofy I relay 503, but relay 503 being energized at thistiine thiscircuit is ineffective." 1 r v Rel-ay 605 upon operating supplies holding ground for certain relays'of" the sender, es-.

.tablishesacircuit for relay 608 extendin'gfi'sw" from battery, through the winding of relay 7 608, the back contact of relay 609,'conductor 70 1 tovground at the intermediateleft contact of'relay 605 and establishes a circuit for relay 7 00 extending fror'n 'batterythroug'h the"f winding ofrelay :700 ','the right'jba'ck, otem] of relay-701, conductorg702gthe rightfZh'a'ck contact of relay 624, conductor-6111, theback contact of relay 703, conductOrfTOL to: ground at the' intermediate left c'ontact 'of='-relay 605. 1105 I Relay 700 energizes in this c ircui'tprepar'atory tofcontrolling incoming brush selection at the incoming selector 325 in which the I trunk of-Fig.-3terminatesi Y i I Settmg the s ender 77692-815678:

- Preparatory to registering the number :ot the desired subscribers line on'the reg sters of thesendertheoperator; depresses the key' 123 thereby closing a circuit for relay "1"] 9 g :1 15

which may be, traced froin battery through the Winding ofrelay:119,'thelower back con-v tact of relay 1124:; fr0nt contact of key .123,

conductor 125, lower contact of relay} 214C,

118to the operators headset and establishes an operating :circuit,forsrelay'r6l2 of the .130

i scribedhereinafter. Rela eae alsoestablishesfaholding circuit for transfer relay of the trunk finder 45 0, .contact530 of relay 'ated a fundamental circuit is established be- "tween. the sender and the incoming selector '32 which' 'inay be traced in partfroin bat-- tery through the control relay (not shown) of the'incoining selector, over the upper back contact' of-"relay 311,the upper back contact of relay'312,"condu'ctor 313, brush 415 =512,"brus h 52 1 of thesen'der finder 550, conductor 531; the right back'contact of relay- 626, condt i'ctor 627, the' inner left normal fcontactsgof relay '767, the -ba ck 'contact of 'Trelay708, the 'leftwindingof polarizedjover- "flowf relay 709, ithe winding of "sender fistep- 'lay 623, the leftback conta'ct of relay 626, coni Q xductorr- 627, brush 520- of thfsender finder 5 50, contact 5320f relay 512, bru'shfi414} of trunk finder 450, conductor 420; thelower backcbntacts' f relays 312 andv 311' to ground "in the incoming "selector." The control re lay of "the incomin'gselector and sender" step-.

registermay now take place. The "manner, in which this is accomplished-will be de';-"

ping relay 710 energizejin this circuit but oyerflowirelay 1709 being polariiedjdoes not "receive .eurrem -ia n the right direction to 'operate'iat thi's time, g'lhe setting of the selector undenthe control of the thousands extending from' batterythrough the "winding of'relay 7O0', the right winding 7 of transfer-1 relay 701, the inner 1 right contact "Qf reIay-TZOO, conducto-r'757 to ground} at the right lcontact. of 'rela'y' 623. 'Relay 701 I does not' hojwever operate i'n thisholding 'c irc'1'1i'tbeing shunted until counting relay 3 7O3 "opeI :ates.k g v I v Theoperator now, proceeds 'to' 'depresfs the No; 3 key to register the hundreds "digit of *the wanted line number. With the N6 3 key'1135' depressedthe 48 volt battery -is connected through low resistance -l30,"overf the lower front contact of'relay 128, t'he contacts of key 135, the inner upper front c'onitact offrelaiy12 8 to the'tip pulsingconductor themes-a previously traced through the fwinding's; of= pulsing relays 617, 618 and 619 I a v{toi- 24yolt battery, Y The direction 'jof-current I nowffiowing' through the windings of these pulsingrelays is' su ch as to operate the polar- I l i'zed relay 619- and since a 'low; resistance I both relays 617 and 618 also operate.

has beenin'cluded in'the operating circuit 1 Relay 617 upon operatingfcloses a circuit from ground at itsf contact over "conductor 621, the right 'ba'ck contact of relay 800, the

front contact-of "relay 811 to "battery through the windingof relay 8 14; Relay 814 operates in this circuit-closing a locking circuit for itself through its windings ";'andthe winding of 812 in series? its own; left frontcontact,the left back contact of relay 815 ping relay 710,}thej right normal contacts of, a relay 707, conductor 711; theleft contact ofre- :Relay' 617 upon operating closeso'a circuit of relay'803 to battery through the right winding of hundreds register relay 816; Re-

lay 816; upon operating looks over its left winding and-left contact, conductor- 8 17 togroun'd at the outer left contact of relayf605,

Relay 619 upon e ergizing closes a circuit extending from ground atfits contact, over condu'ctor 628, the inner'left contact'ofgre- I lay 803 to battery through the right winding of hundreds'register relayj818'. 1 Relay 818 upon; operating locks 'ov e'rfliits left wind 'ingand left contactto groundon conductor a When theoperatorreleases the'd'epr'essed key 135, relays617, v618 and 619'frelease, relay 617fopening theshunt' around the winding of relay 812 whereupon relay"812 operates"in the locking' circuit'of relay 814. f RelaIy 81 2 upon operating now opens at-itsleft back =contactthelocking circuit of relays 811 and 8O3 whereupon; these relays release, relay to ground on onductor 804 (but relay 812 being shunted 'as" long as relay 61'? remains operated does not operate at this time. Be -lay 6181113011 operating closes, a circuit @1 0 .tending'from' ground at its contact, over con- 'ductor 622, the intermediate rlght contact 8Q3 disconnecting the operating circuits of 1 the register relays 'of' the' hundreds register from thecontacts of; the pulsing relays and relay "812' upon operating connecting the ulsing relays to the; wind ings-of the tens register relays.

contacts/of the p No; 7 items "key to registerfthe tens-'- digit of I The operator now proceeds to depress the traced over the tip pulsing conductor through the windings of pulsing relays 61 7,

*618 and 619to the 24 yolt battery; The direction of current now flowing through} the windings of these pulsing relays is" such as to operate polarized relay 619 andsincehigh resistancecl37 hasbeen included=inthe cirg "cuit the current strength is suflicient to oper ate relay 61 7 "but not to I operate relay- 618.

'fromjground atits contact. over conductor 621, the right back contacts'of relays 800V and 811,- the right-frontcontact of relay 814 toibattery throughthe winding of relay. 819. 1 Relay 819 operates in thiscircuit closing a locking {311611111101} itself through its winding andthe winding of relay 815 in series, thejleft front contact'of relay 819,;the right normal, con-v ftacts of relays8081and 807jto groundon con-f du'ctor1804, but relay 815 being shunteclflso l'ongas relay 617 re1nains operated does vnot operate at this time. Belay 619up0n operating closes 'a circuitextending from ground at its contactover conductor 628, the inner left lay 820 upon operatingjlocks overits left winding and left contact to ground on conductor 821.

t its left contacts key 136 closes a circuit from ground through low resistance 138, the

uppermost alternate contacts of relay 128 thence as traced over the ring pulsing conductor to battery through the windings of pulsing relays 614, 615 and 616. The direction of the current flowing is not such as to cause the operation of polarized relay 616, but since only low resistance 188 has been included in the pulsing circuit both the sensitive relay 614 and the marginal relay 615 operate. Relay 614 upon operating merely duplicates the function of relay 617 already described and relay 615 connects ground over its contact, conductor 630, the outer right contact of relay 812 to battery through the right winding of tens register relay 822. Relay 822 upon operating now locks over its left winding and left front contact to ground on conductor 821.

When the operator releases the depressed key 186 relays 617, 619, 614 and 615 release,

relays 617 and 614 opening the shunt around the winding of relay 815 whereupon relay 815 operates in the locking circuit of relay 819. Relay 815 upon operating now opens at its left back contact the locking circuits of relays 812 and 814 whereupon these relays release, relay 812 disconnecting the operating circuits of the register relays of the tens register from the contacts of the pulsing relays and relay 815 upon operating connecting the contacts of the pulsing relays to the Windings of the units register relays.

The operator now proceeds to depress the No. 9 units key to register the units digit of the wanted line number. With the No. 9 key 139 depressed 48 volt battery through resistance 130 over the lower front contact of relay 128 is connected over the left contacts of key 139, the upper alternate contacts of relay the winding of relay 823. -Relay 823 upon operating locks in a circuit extending through its winding and the Winding of relay 805 in series, the front contact of relay 823, the left normal contacts of relays 808 and 807 to ground on conductor 804, but relay 805 being shunted so long as relay 614 remains operated does not operate at this time. Relay 615 upon operating connects ground over its l contact, conductor 630,the outer right contact of relay 815 to battery through the'right winding of units register relay 824. Relay 824 operates and locks over its left Winding and left contact to ground on conductor 817. Relay 616 upon operating connects ground over its contact, conductor 631, theinner right contact of, relay 815 to battery through the right Winding of units register relay 825,

this relay looking through its left Winding and left contactto ground on conductor 817..

Upon the depression of key 139 a circuit is also established fromground throughlow resistance 134, high resistance 140, the right contacts of key 139, the inner upper front contact of relay 128, thence as traced over the tip pulsing conductor through the Wind'- ings of pulsing, relays 617 618 and 619, butdue tothe direction and strength of the cur rent flowing over this conductor only pulsing relay 617 operates duplicating thefunction of pulsing relay 614 already described;

When the operator releases the depressed key 139, relays614, 615, 616 and 617 release, relays 614 and 617 removing the shunt from around the winding of relay 805 whereupon relay 805 operates in the locking circuit of relay823. With relay 805 operated a circuit is established from 48- volt battery battery through the'winding of marginal relay 808, the right. front contact of relay 805 thence over conductor 529 and as traced over the ring pulsing conductor to the upper alternate contacts of relay 128, the upper normal contacts of key 141 to 24 volt battery 7 through the winding of high resistance polari zed relay 143. Relay 143 operates in this circuit, but due to its resistance relay 808 does not receive sufficient current to operate at this time.

With both relays 142 and 143 operated a circuit is now established from ground at the front contact of relay142 over the contact of relay 143. to battery through the winding of-relay 144. Relay 144 upon energizing locks over its upper front contact to ground at the inner lower front contact of relay 119 and connects directground over'its upper front contact between the winding of po-' larized relay 143 and the winding" of the marginal relay 8.08 whereupon relay 808 op erates looking over its left alternate con"- tacts, the left normal contacts of relay 807 to ground on conductor804. At its left, nor- V ductor 107 whereupon relay 119 releases in turn releasing relays 124, 127, 128 and, 144.

"45 I erated thereover, Upon-the energization' of 7 mal relay 808 also opens thelocking circuit of relays805 and 823 whereupon these relays release opening the circuits previously traced over which relay 808 of thesender and polarized. relays 142 and 143 operated. Relay '808 at its right front contact also prepares a'circuit for relay which will be described hereinafter.

Relay 142 upon-releasing establishes a shunt circuit around the winding of .relay 119 Which'may be traced from, ground at the back contact of relay 142, the lower front contact of relay 144, winding of relay'119,

upper front contact ofv relay 119, right'contacts of'release key 126 togroundon con- Uponthe release'of relay 124 the guard la'rnp 132 becomes extinguished asa signal that the call has been completely registered at the sender. If the talking key 102 has been restored to its normal position thefcircuit of relay 200 will at this time be'opened since its alternative holding circuit through the front contact of relay 119 is now broken and relay 200 upon releasing will open the holding circuit of cordnrelay 103 disconnecting, thetip and ring contactsof' plug 118 from. theconductors extending to "the operators f key pulsing cir'cuit andestablishingithe continuity of the talking circuit between the tipand ring contacts of plug 100 and'the v tip andring contacts of plug 118. The key 7 set, is nowcompletely disconnectedfrom the cord circuit,and may be used with another cord'circuit of the operators position to con:

trol the setting up of another connection.

' lncomz'ag 'bmsh'- selectionf "It will be recalled that following the a pletion of the thousandsdigit registration transfer relay 7 00andj relay'623'became energized and that the fundamental circuit ex.-

i tending to theiincoming selector 325 was-es;

tablish ed and sender stepping relay 710 oprelay 710 with the thousands-register relay 813 energized a circuit is establishedforj operating the N010 counting relay 712 extend ing from battery throu h the winding of relay 712 over conductor%14, the outerright back contacts of transfer relays 715and 716,

the No. 0 lead 713, lead 713fFig. '8,'the' outer I i right back contacts of thousands register relays 826 and827, theouter left back contact of thousands register relay 828, conductor 829, theouter rightcon'tact of transfer relay 700, conductor 717, the right back contact of relay 603, conductor 632, the front contact of stepping relay 710 to ground'at the left backcontact 'oftransfer relay 718. Relay 712 upon operating locks in a circuit 7 through its winding and the windings of relays 7 03-and708 in parallel, the front contact of relay 712 to'ground at the left front this time.

contact of relay 700, Relays 703 and 708 i being shunted by groundover the front contact of stepping relay 710 do not operate'at Atthe incoming selector the control relay 7 operates in the wellknown inanner over 'the I fundamental circuit and causes the selector switch shaft to be driven upwardly in a brush selecting movement. As the switch approaches its first brush-selecting position the switch commutator shunts down the sender around the right winding of transfer relay n, .701 whereupon relay 701 energizes 1n the-locking circuit of relay 700 and closes a locking circuit for'itselfover its left winding and inner left front contact, conductor 719 to j ground at the inner left contact of relay 605.' 9 Relay 624 also opens-the circuit of relay 623 which releases opening the fundamental circuit anjcl'the locking circuit of transfer relay 700; Relay 7 00nowr eleases'in turn releasing V operated counting relays 7 03, 7 08and 7 :12 and i relay 624.; j v J v Y 1 [acquaint group selectim'z Aj'circuit is now established for the transfer relay 720 preparatory-to controlling in- 0; coming group selection, which circuit may be traced from battery through the winding of relay 720, right back contact oftransfer relay 721, right front 'contactof transfer relay 701,

- conductor 702,lright baclr contactsof relay in" 624, conductor 611,-back contact of relay 7 03 I to ground on conductor704. If the hundreds digit has-been registered at this time andre- 811 has released a circuit will be establishedfor slow operating relay 623 extending 1 Li throughthe' winding of relay 623, the left contact of relayv 624, conductor 625,-the left front contact of transfer relay 701, the'outer right normal contacts of transfer relay 718, conductor 722, the left back contactof relay 811 to ground on conductor 804. Assoon as relay623 operates it againestablishes the fundamental circuit as previously traced causing the energization' of the selector con trol relay and of the sender stepping relay 710, and establishes-a locking circuit for relay 720 extending from battery through the winding of relay 720, theright Winding of relay 721, the inner-right contact of relay 7 20,

conductor 7 57 to groundat theright contact of relay 623. Relay 72l being shunted at this time over the circuitpreviously traced register relay 813 andhundreds register re.-

lays 816 and 818 are operated thecircuitfor the-No. 2 counting relay 723 is established from battery through the winding of this relay, the back contact of the No. 2 relay, the No. 2 control lead 725, lead 725 Fig.8, the right back contact of hundreds register relay 830 the outer right back contact of thousands register relay 828, theright front contact of relay 813, conductor 831, the left contact of transfer relay 7 20, conductor 717, the right back contact of relay 603,.conductor 632, the front contact of stepping relay 710 to ground at the left back contactof transfer relay 718. Counting relay 723 operates in this circuit and locks through its winding and the winding of the No. 2 counting relay 7 24:, the contact of relay 723 to ground at the outer. right contact of transfer relay 720, but relay 724 being shunted by ground over the contacts of stepping relay 710 does not operate at this time. 7 r I At the selector the control relay again causes the selector shaft toadvance in abrush tripping and group selecting movement, the switch commutator shunting down the sender stepping relay 710 as it approaches the first group selection position; VV hen the stepping relay 710 becomes shunted and deenergizes the shunt aboutthe No. 2 counting relay 7 24- is opened and relay 7 24 energizes extending the operating lead 725 to the winding of the No. 1 counting relay 726. In the well known manner in response to the next shunting impulse atthe selector as it reaches its second group selection position the No. 1 counting relay 727 operates in the locking circuit of counting relay 726 again extending the operating lead 725 to the lead 713 and thence as previously traced to battery through the winding of the No. 0 counting relay 712. In response to the third shunting impulse at the selector the counting relays 703 and 708 operate in the locking circuit of the No. 0 counting relay 712. Relay 708 upon operating opens the fundamental circuit thereby releasingthe selector control relay to arrest theadvance of the selector. The selector has therefore tripped its first set of brushes andadvanced them into contact with the first set of terminals of the third group in its lowermost bank. Relay 703 upon operating again establishes the circuit of relay 624,'which upon operating opens the shunt around the right winding of transfer relay 721 whereupon relay 721 energizes in the locking circuit of relay 720 and closes a locking circuit for itself over its left winding and inner relay 624;. r

left contact to ground on conductor "719i. Relay624= also opensthe ci rcuit of relay 623 which releases opening the fundamental circuit and the locking circuit of transfer relay 720. Relay 720 nowreleases in turn re-' leasing all operated counting relays-and I iivirrirl'brush selection/ A circuit is now established for the'trans fer relay 728 preparatory to controlling final brush selection at the final selector which circuit may betraced from battery through the winding of relay 728, inner right back contact of transfer relay 718, right front contacts of transfer relays 721 and 701, conductor 702, right contact of relay 624C, conductor 611, back contact of re lay 703 to ground on conductor 704:. A circuit isfnow established for'slow operating relay 623 extending from battery through the winding of relay'623, theleftcontact of relay 624C, conductor 625, the left front contact of relay 701, the outernormal contacts of; relay 718, conductor 722, the left back contactofrelay 811 to ground onconductor 804." Relay 623 being slow to operate does I not energize until'suflicienttime has elapsed to permit the lncominglselector to hunt for an idle trunk in the selected group 'trmi nating in a final selector hayingaccess to of relay 728, the right winding of relay 718, inner right contact of relay 728, conductor 757 to ground atthe right contact of relay 623. Relay 718 being shunted'a't this time over the circuit previously traced through the right back contact of relay 624 does not operate in this locking circuit.

Having assumed that the hundreds digit registered was 3 and that therefore hundreds register relays 816 and-818 are operated a circuit for the No. 3 counting relay 731. is established from battery through he winding of this relay, the back contact of the No.'

3 counting relay 732, No. 3 control lead .729, lead 729 Fig. 8, the outer right front contact of hundreds register relay 818, the right front contact of hundreds register relay 816, conductor 832, the left front con tact of transfer relay 728, conductor 717,

the right back contact of relay 603, conductor 632, the contact of sender stepping relay 710 to ground at the left backcontact of transfer relay 718. Counting relay 731 operates in this circuit and locks through counting relay 7 32 to ground at the outer itswinding;and-theawindin of at No.3!

right-"contact of transfer relay 728, but re-V flay 7 32' being shunted byiground overthe "contact's'ofistepping relay 710' does iotop: jerate atk'this time.

At {the final selector -controjl' relay.

I establishes in the-Well known mannerithe circuit of the high-speed up-driye magnet to advance theswitch shaft in a. brush: lselectcing'imovement; When the shaft approaches its first brush selection position the switch commutator shunts downthe sender'steppi'n-g i relay 710, Whichlupon releasing opensthe v energizes ntheilocking circuit of counting shunt aboutcounting Irelay17 32 which now relay. 731, and extends; the operating lead .fl729uto: thawinding of the, N; 2 counting relay" 7 23.; 111] the :manner previously described in response to further shunting impulses as the selector shaftadvances, counting relays723, 724, 726, 727, 712,703 and a 1.708 operate in: the manner previously de-' V scribed. -Belay 708 upon operating opens the fundamental 1 circuit thereby releasing theselectorcontrol relay to arrest; the'fur I :thergadvance ofthe selectorswitchi;shaft. The selectorhasno'w been advanced to. a

' V lecting -moVement;

-positio n to-trip itsfourth set of brushes when" it is later advanced in agroup se rRelay fl703- upon, operating again, establishest'he circuitfiof relay 624: which iii-turn opens the shunt around the right Winding of transfer relay 718. :Relay 718 110W; energizes inthe locking/circuit of relay 728 and: closes a locking circuit for itself over 7 its left winding and inner left front contactto ground on, conductor 719-. Relay 624-also opens the circuitof relay 623 which "releases opening the fundamental circuit and the locking circuit ofgtransfer relay 728. ,"Relay 728 now releases in turn re- Winding of relay 716, the right-back contact of'transferrelay 733, the inner right front contact of relay 718, the right front contacts jof relays 721 and 701, conductor 702, right contact of relay 624, condu ctor 61 1, back con.-

'tact ofrelay .703 to groundon conductor l.

A; circuit is now established for slow operating relay 623, if at this time the tens digit has been fully registered, which may be I traced from batterythroughthe Winding of relay 623, the left contact of relay 6 24, conductor 625, the --left front contact of relay 701, the outer right alternate contacts of transfer relay 7l8 the left back contact of transfer relay 7 33, conductor 833 the left back con tact of relay 814, Which Will now. be deen-- ergized ifthe tens'digit has been registered," to groundon: conductor 804. As "soon I as relay 623 operates, it a,gain-*establishes the fundamental circuit causing the operation of the selector control relay and of the: sender Stepping relay ,?i 'lld. establishes a lockin Circuit for r 6 -extending ifronibat'tery a through the, Windingof relay 716, the'right Winding of relay 733, the inner right front contact of relay 716, conductor7 57 .to ground I 1 at the right front. contact of relay 623. Relay 733beingshunted at this time over the circuit previously traced through the right back con tact of relay 624ldoes not operate in this locking circuit.

Having assumed 'thatthe tens digit regis tcred was 7 and thatt'ens register relays 820 and 822 have been operated a circuit for the i.

No. 2 counting relay 723 is established from bat-ter Windin of this rela 1 the back contact ofthe No. 2-'counting'relay 724,'the No. V

2;control lead'725, lead725 Fig. 8, the inner rightrback contact of tens register relay 835,

theright back contact of, register relay 836, conductor 837, the left contact .of transfer relay 716, the frontcontact of sender step;

ping relay 7l0,'conductor 632, the-right back contact of relay603, conductor .7l7,fthe left '90; the right front'contac'tof register relay 82Q, r I

back contactof transfer relay 7 28 .to ground at the outer left front contact ofJtransfer relay 718. Counting" relay 723 operates in this circuit and locksthrou g'h its Winding and the inding of the 'No.-12- counting relay 72%, the Contact of relay 7 23fto ground at the 7 intermediate; right front contact "of a transferrelay 716, but relay 72st being shunted by ground over the contacts of stepping relay 710 does not operate at this time.

At the selector the control. relay againcau'sesthe selector shaft to advance in a'brush. tripping and group selecting movement, the switch commutator shunting down the sender steppingrelay710 as .it approaches the first group selection position. When the sender stepping relay 710 becomes shunted and-deenergizes the shuntaround the No. 2 counts ing relay-724is opened andrelay 724 energizes extending the operating lead 'Z25Jto battery through the Winding of the N0. 1" countingrelay 726. In: response'to the'further advance of the selector switch shaft counting relay 726 and 727 become energized, the

No. 1- counting relay 727" extending the'opf crating lead 725 to the No. 0 operating lead 713 thence over the outerrightfront con-tact] .of transfer relay 7l6, conductor 7 35', the right v front contact oftens register relay- 822, conductor 838,the right back contact of the-No. 9 counting relay 736 to battery through the Winding of the No. 9counting relay 737. In the Well known manner as the selector shaft advances countingrelays 738-t0. 745 operate, I 

